The present invention relates to an optical lens or glass having a label and/or marking on the front surface and/or rear surface, which is directly visible under all lighting conditions.
Optical glasses, such as spectacle lens or watch glasses, mostly have a label that indicates the glass manufacturer. This feature is very important, because it is to be possible to recognize from viewing the glasses that a brand product or an authentic product is involved, or the glass manufacturer is to be immediately visible.
It may be gathered from this that such labels must be applied to the above-named glasses in a permanent form without changing the optical properties of the glass.
Various methods are known for applying labels. A distinction is made in principle between methods in which dyes and, in particular fluorescent dyes are applied to the surface or introduced into the surface, and methods in which engravings or the like are introduced into the surface, that is to say the optical surface is provided with a small impression etc.
In the case of methods in which engravings are introduced into the surface, a distinction is made between contact and non-contact methods. Whereas the contact methods are generally executed with the aid of fine mechanical methods, as in the case of the use of stylus, non-contact methods use the interaction of light with the surface to be labeled, or of a layer—the layer causing interaction or reinforcing it—which is applied (temporarily) to the surface and has a particularly effective interaction with the irradiated light.
In both cases, these are expensive methods which require a careful handling of the glass surface and/or a complex apparatus.
So-called breath marks are known, i.e., various substances which have a different wetability with the glass surface being applied in the form of the label and/or marking by way of a die for the purpose of labeling and/or marking the optical glass. Such labels and/or markings have the disadvantage that they can hold only for a short time, and also the entire method is very complicated.
A method that is likewise known produces labels and/or markings on the glass surface with the aid of masks or stencils that have an aperture in the shape of the label and/or marking. The suitable substance is vapor deposited through the aperture so as to produce the label and/or marking on the glass surface. However, the glass treated with the aid of such a method exhibits a label that is not properly sharp at the edge because of the distance—albeit only a small one—between the lens and stencil.
EP-B1-0 103 217 further discloses a spectacle lens having a reflection-reducing layer, the label and/or marking being incorporated in the form of at least one region cut out from the reflection-reducing layer. Applied in the region to be cut out for the label and/or marking is a substance that is bonded in a fashion such that it can be wiped away and which is wiped away at a later point in time together with the reflection-reducing layer vapor-deposited on it.
The disadvantages of this method are the restrictive application only for lenses, the reflection-reducing layers occur and, in addition, the fact that the application of the substance that is bonded in a fashion such that it can be wiped away is expensive because the large number of items.
A similar lens is also described in EP-B1-0 307 874, mask inscription by way of an excimer laser being used in order to produce the label and/or marking. An excimer laser is used to irradiate a mask that incorporates the shape of the label and/or marking as a cutout, and the latter is imaged onto the surface of the spectacle lens.
The method has the disadvantages that it is very expensive, and that in the course of mask inscription most of the laser energy is reflected unused at the mask or converted into heat. Moreover, the label and/or marking engraved with the aid of this method is visible only in reflected light.